Between the Mountains

[LoTech]

Back in the day (20+ years ago) I used to get Tri-Cities TN and Huntington WV channels here in eastern Kentucky pretty good. I guess VHF analog bends over the terrain pretty well. In order to get it, though we had to put an antenna on top of the hill behind the house with about 2500 feet of ladder-line antenna wire connecting it to the TV. I don't know how the signal carried that far because when I read up on coaxial cable, they say even RG11 signal becomes unusable after about 400 feet even with an amp.

Anyway, the stations are still broadcasting, and TV Fool says that the spot on top of the hill where my antenna used to be can receive about 20+ digital channels and a few analog low power UHF channels.. In the valley where my house is I can only get a local CBS affiliate that is about 19 miles away.

Is there any way to get the signal from those channels down into the valley from the top of the hill? From what I've read, digital signals definitely won't carry that far on coax, and the signal loss from an amplified passive repeater will be too great from that far away.

[Terryl]

There is a way but it’s a bit expensive, and that is to use a fiber optic link, you put the modulators at the mountain top with all the antennas and then run the fiber down to your de-mods, this is how some of the cable head ends work.

You can run fiber for miles before you need a repeater.

Looky here. http://www.dawnfiber.com/site_html/***Show***_Catalog=DAWNfiber_Category=All_SubCat=A ll_.html

[LoTech]

I checked TV Fool again, and it says I can get signal for about 7 channels close to my house, but it's really low (-18.7 NM(dB), -109.6 Pwr(dBm) to -24.1 NM(dB), -114.9 Pwr(dBm) all 2edge). The signal would be diffracted over the top of the hills around my house, so would it be possible, and if so what would I need in order to get these channels?

[Terryl]

Well that’s going to be tough as the UHF stations won’t diffract that easy and they don’t travel as far as the VHF stations do.

What you can do is get the highest gain VHF antenna you can find, then do the same for UHF, then a VHF/UHF summing amp can be mounted at the mast, and the mast should be as high as possible (over 50 foot get a tower) then a good inline amp can be used to eliminate the line loss from the mast/antenna (tower) and good coax (RG-11) can be used.

In some cases we used 2 or 4 high gain antennas cut to specific TV channels then run to a antenna/channel combiner, but this gets expensive.

Overall the best thing is to get the antenna(s) as high as possible; this cuts down on the ground clutter.

You must remember that the Earth is round, and the further you get away from the TV transmitters the higher up from the ground the signal is, (due to the curvature of the Earth) this is why most TV transmitters are on top of a mountain or very tall tower or building.

Most VHF TV signals can be received at around 150 miles away from the transmitters (depending on terrain) with out adding expensive equipment to receive them, UHF will be half that as the higher in frequency you go the less distance it will travel, if you put 2 transmitters on the same hill at 50,000 watts and one is VHF the other UHF, the UHF will only be able to cover about half the area that the VHF one can, this is why the higher UHF station transmitters are up to 5 million watts output, this is to try and cover the same area as the VHF stations.

Then we come to the problem (that they found out too late) that the digital signals don’t cover the same area as the old analog ones did.

OK too much coffee.

In my opinion with out spending all your green stamps on antennas, combiners, amps, fiber, towers and racks of other equipment, get the biggest highest gain UHF/VHF antenna you can find and mount it as high as you can afford and use good coax, also a good rotor would help.


Sorry I ramble too much in the morning...